1. Field of the Invention
The present invention relates to an electrochemical cell having a cathode of lead (II) fluoride and to methods for making a cathode having such depolarizing material.
2. Description of the Prior Art
Electrochemical cells having a pair of electrically conductive electrodes of dissimilar materials immersed in a conductive solution, generally sea water, are commercially available. The most common employ a magnesium anode and a silver chloride cathode. The cathode of this cell is relatively easily fabricated because silver chloride can be extruded through a die while hot to form a self-supporting, integral structure. However, silver chloride is highly expensive, so that a cheaper electrode of similar characteristics would be desirable. Furthermore, in many applications, an electrode capable of producing more power from the same volume or weight of material would be desirable where minimum space or weight is required.
Much work has been done with similar cells employing copper (I) chloride as the cathode material, and such cells have been manufactured for use in buoys or radiosondes. In actual use, however, it has been found that even though copper (I) chloride is considered relatively insoluble, this compound is affected by moisture. It is now believed that hydrated chlorides are first formed, which then absorb water. In any event, the copper compound, when exposed to water, tends to migrate from the cathode to the anode, so that the copper compound comes in contact with the magnesium and plates out thereon. This internal short circuiting effect has caused many of such batteries to heat up and because hydrogen is generated, to catch on fire, sometimes resulting in an explosion. Thus, other cathode materials, not subject to attack by water, are highly desirable.